Normally, only one bursa is in the heel, between the Achilles tendon and the heel bone (calcaneus). This bursa may become inflamed, swollen, and painful, resulting in anterior Achilles tendon bursitis.

Abnormal pressure and foot dysfunction can cause a protective bursa to form between the Achilles tendon and the skin. This bursa may also become inflamed, swollen, and painful, resulting in posterior Achilles tendon bursitis.